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| United States Patent |
5,629,261
|
|
Narayanan
, et al.
|
May 13, 1997
|
Free-flowing, non-dusting water dispersible granules of a
water-insoluble, hydrophobic agriculturally active chemical having low
friability and superior crush strength
Abstract
A free-flowing, non-dusting water dispersible granule (WDG) of a
water-insoluble, hydrophobic agriculturally active chemical having low
friability and superior crush strength for delivery to a desired site as a
stable, rainfast suspension in water, without foaming.
| Inventors:
|
Narayanan; Kolazi S. (Wayne, NJ);
Fu; Edward (Kinnelon, NJ)
|
| Assignee:
|
ISP Investments Inc. (Wilmington, DE)
|
| Appl. No.:
|
512742 |
| Filed:
|
August 8, 1995 |
| Current U.S. Class: |
504/361; 71/904; 424/409; 504/367 |
| Intern'l Class: |
A01N 025/14 |
| Field of Search: |
504/116
424/409
71/904,DIG. 1
|
References Cited
Assistant Examiner: Bembenick; Brian G.
Attorney, Agent or Firm: Katz; Walter, Maue; Marilyn J., Ward; Joshua J.
Claims
What is claimed is:
1. A wet paste composition for making a free-flowing, non-dusting water
dispersible granule having low friability and superior crush strength of a
water, insoluble, hydrophobic agriculturally active chemical capable of
forming a stable, and active rainfast suspension of said chemical in
water, without foaming, for delivery to a desired site by effective
disintegration of the granules, comprising, by weight:
(a) as active component, a water-insoluble, hydrophobic, agriculturally
active chemical, 10-90%, optionally, with a filler at the lower end of
said range,
(b) as disintegrant, cross-linked polyvinylpyrrolidone, 1-6%,
(c) as film-former, a rainfast, water-insoluble polymer, 1-5%,
(d) as penetrant, a C.sub.8 -C.sub.18 alkyl pyrrolidone, 0.5-10%,
(e) as suspending agent, an anionic oil soluble surfactant, 0.2-4%,
(f) as fluidizer for a hydrophilic medium, an aromatic petroleum oil,
1-20%,
(g) a wetting agent, 1-10%,
(h) a dispersant, 1-20%, and, optionally
(i) water, 1-10.
2. A composition according to claim 1 wherein (a) is 70-80%, (b) is 2-4%,
(c) is 1.5-5%, (d) is 1-6%, (e) is 0.5-1.5%, (f) is 5-10%, (g) is 2-4.5%,
and (h) is 4-16%.
3. A composition according to claim 1 wherein (a) includes a filler.
4. A composition according to claim 1 wherein (c) is N-octylpyrrolidone,
(e) is calcium dodecyl benzene sulfonate, (h) is naphthalene formaldehyde
condensate sulfonate and (g) is lignin sulfonate.
5. A composition according to claim 1 wherein (c) is a copolymer of vinyl
pyrrolidone and a C.sub.4 -C.sub.30 alpha olefin.
6. A water dispersible granule which is made by extruding and drying the
wet paste composition of claim 1.
7. A water dispersible granule having a cone dispersion of less than 55, a
Friability Index of greater than 90, and a crush strength of greater than
10.
8. A water dispersible granule according to claim 6 in which drying removes
substantially all of the (f) and (i) components of the wet paste
composition of claim 1.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to water dispersible granules (WDG) of
agriculturally active chemicals, and, more particularly, to free-flowing,
non-dusting WDGs of water-insoluble, hydrophobic agriculturally active
chemicals, which have low granule friability and superior crush strength,
and which form stable, non-foaming suspensions in water, for delivery of
such chemicals to a desired site.
2. Description of the Prior Art
WDGs are important delivery vehicles for active agricultural chemicals
because, unlike emulsion concentrates, they are organic solvent-free, do
not have dusting problems present with wettable powders, and can be
transported more economically than suspension concentrates. WDGs are
prepared by water-bonding particles of the active component. However, in
the absence of a binder additive in the system, the granules will
gradually lose cohesiveness as the water content is reduced by
evaporation. A useful binder additive, therefore, must provide for
effective granular crush strength and low friability, while enabling the
granules to form stable suspensions in water during use, without
deleterious foaming as a result thereof, and to quickly dissipate its
binding action when immersed in water.
Ligninsulfonate has been considered the binder of choice in WDG systems.
Polyvinylpyrrolidone, in combination with urea, has been suggested for the
same use (Canadian Patent 1,209,363).
However, there is a need for new and improved WDG systems in which a
combination of components therein will provide free-flowing, non-dusting
granules having low granule friability and superior crush strength, and
which will form stable suspensions in water without deleterious foaming.
In particular, it is desired to provide for effective delivery of
water-insoluble, hydrophobic agriculturally active chemicals to a desired
site for application of a rainfast film on the infected plant.
SUMMARY OF THE INVENTION
A wet paste composition for making a free-flowing, non-dusting water
dispersible granule (WDG) having low friability and superior crush
strength of a water, insoluble, hydrophobic agriculturally active chemical
capable of forming a stable, and active rainfast suspension of said
chemical in water, without foaming, for delivery to a desired site by
effective disintegration of the granules, comprising, by weight:
(a) as active component, a water-insoluble, hydrophobic, agriculturally
active chemical, 10-90%, optionally, with a filler at the lower end of
said range,
(b) as disintegrant, cross-linked polyvinylpyrrolidone, 1-6%,
(c) as film-former, a rainfast, water-insoluble polymer, 1-5%,
(d) as penetrant, a C.sub.8 -C.sub.18 alkyl pyrrolidone, 0.05-10%,
(e) as suspending agent, an anionic oil soluble surfactant, 0.2-4%,
(f) as fluidizer for a hydrophilic medium, an aromatic petroleum oil,
1-20%,
(g) a wetting agent, 1-10%,
(h) a dispersant, 1-20%, and, optionally,
(i) water, 1-10%.
The WDG is made by extruding and drying the wet paste composition,
effectively removing components (f) and (i) from the wet paste
composition.
DETAILED DESCRIPTION OF THE INVENTION
(a) The agriculturally active chemical in the composition of the invention
is a water-insoluble, hydrophobic herbicide, insecticide or fungicide; for
example, chlorothalonil, such chemicals ordinarily present difficulties in
formulating the chemical in a WDG which is dust-free, of high hardness and
low friability/attrition, and of producing a suitable stable dispersion
for delivery to a desired site which is biologically effective and
rainfast.
(b) The disintegrant component of the WDG formulation of the invention is
crosslinked polyvinylpyrrolidine (XL PVP).
(c) The film-forming, rainfast component of the composition of the
invention suitably is a water-insoluble polymer preferably a copolymer of
(i) a crosslinked or non-crosslinked N-alkenyl lactam homopolymer or
copolymer in which the lactam unit of the polymer is represented by the
formula
##STR1##
wherein R is C.sub.3 to C.sub.6 alkylene optionally substituted with
C.sub.1 to C.sub.20 alkyl; R.sub.1 and R.sub.2 are each independently
C.sub.2 to C.sub.20 alkyl or hydrogen and n has a value of from 0 or 2,
and mixtures thereof, and (ii) a C.sub.8 to C.sub.30 comonomer selected
from the group of an alkenoic acid; an alkenylanhydride, ester, ether,
amino ester or amino amide and an alpha mono- or di- olefin.
(d) The penetrant is a C.sub.8 -C.sub.18 alkyl pyrrolidone.
(e) The suspending agent herein is an anionic oil soluble surfactant such
as calcium dodecyl benzene sulfonate.
(f) The fluidizer for a hydrophilic medium is an aromatic oil.
(g) The wetting agent is a lignin sulfonate, etc.
(h) The dispersant suitably is a naphthalene formaldehyde condensate
sulfonate, etc.
A preferred film-forming, rainfast polymer is a copolymer of vinyl
pyrrolidone and a C.sub.4 -C.sub.30 alkyl alpha olefin, preferably
a>C.sub.8 alkyl alpha olefin.
2. Preparation of WDG (Granulation Procedure)
(a) The weighed ingredients of the WDG/simulation (a total of 200 g to 1
kg) were mixed in a V-shell blender for 10 min. and transferred to a
24-inch pan granulator set at an angle of 50.degree. and a speed of 13
r/min. Granulation was effected by spraying the ingredients with tap
water. After granulation, the sample was dried in an oven at 40.degree. C.
for at least 6 hour to reduce the moisture level from 10-15% to under
1.5%. Finally, the sample was sieved to yield a free-flowing, non-dusting
product having a particle size between 10 and 40 mesh (0.425 mm to 2.0
mm). The granules also can be made by extrusion followed by drying of the
extruded product.
(b) Extrusion is a preferred process (See Examples A through F below.
EXAMPLE A
The following ingredients were mixed dry in a twin (V-) shell blender for
10 minutes and ground through a disc mill/air-milled in a two inch
micron-Master jet pulvarizer at a feed rate of 20 g per minute and an air
pressure of 100 psi.
______________________________________
Ingredients Wt., g % by Wt.
______________________________________
Carbaryl, technical grade
149 74.5
Dipotassium hydrogen
10 5.0
phosphate (buffer)
Agrimer XL .RTM., disintegrant
8 4.0
Dispersant 1, Reax .RTM. 45 A
16 8.0
Dispersant 2, Lomar .RTM. D
12 6.0
Wetting agent, Morwet .RTM. EFW
3 1.5
Foamaster soap L .RTM., defoamer
2 1.0
Total 200 100.0
______________________________________
160 g dry milled charge was transferred to a 2 L Hobart planetary mixer
bowl. 40 g Agrimax 3H was added to the charge gradually, while the stirrer
in the Hobart Mixer bowl was set at speed 2. Agrimax 3H was added over a
period of 5-30 minutes. The sample appeared extrudable after the addition
of .about.38 g Agrimax 3H.
The wet paste (145 g) was loaded into a laboratory extruder (LCI Benchtop
granulator, which is a basket type extruder with adjustable speed and
interchangeable screens, and sample was extruded without compression, with
speed at maximum setting (10) and screen opening at 1 mm. Sample extruded
well producing short extrudate without sticking. As the mixing time
increased, the wet mass appeared wetter and sticky. Wetter granules were
longer and were moderately sticky. The wet granules were dried in a
laboratory fluid-bed for 15-30 minutes at 40.degree. C. The dried granules
were sieved through 10 and 40 mesh screens. Following fractions were
obtained.
Wt. retained on 10 mesh screens=31.2 g
Wt. retained on 40 mesh screens=110.63 g
Wt. retained on Pan=1.36 g
Total wt. recovered=143.19 g
% -10+40 granules=110.63/143.19=77.3%
The granule was evaluated for ease and quality of dispersion and
friability. Imhoff cone dispersion index was found to be <0.5, Filtration
suspension index was 73%, and friability index was 98%.
EXAMPLE B
Example A was repeated except 2240 g of the dry milled charge was
transferred to a 4L Hobart mixer in 4 equal batches of 560 g, using an
average of 22.85% Agrimax 3H in the wet mix (i.e., a total of 663.3 g or
an average of 165.8 g per batch), instead of 20%. 2800 g wet paste was
extruded in 4 batches, all batches of extrudates were combined and dried
first in a laboratory fluid-bed for 15-30 minutes at 40.degree. C.
Followed by a vacuum oven at 50.degree. C. for 24 hours. The dried
granules were sieved through 10 and 40 mesh screens. Following fractions
were obtained.
Wt. retained on 10 mesh screens=21.4 g
Wt. retained on 40 mesh screens=2135.1 g
Wt. retained on Pan =91.6 g
Total wt. recovered =2248.1 g
% -10+40 granules=(2135.1/2248.1)100=95%
The granule was evaluated for ease and quality of dispersion and
friability. Imhoff cone dispersion index was found to be <0.5, Filtration
suspension index was 93.6%, and friability index was 95.3%. The commercial
flowable `Sevin` formulation containing 27% active ingredient showed
Imhoff cone dispersion index <0.5, and filtration suspension index 90.1
EXAMPLE C
Example A was repeated except the dry charge was as shown in Table 1 below:
______________________________________
Ingredients Wt., g % by Wt.
______________________________________
Chlorothalonil, technical grade
171 85.5
Agrimer XL .RTM., disintegrant
8 4.0
Dispersant 1, Reax .RTM. 45 A
10 5.0
Dispersant 2, Lomar .RTM. D
6 3.0
Wetting agent, Morwet .RTM. EFW
3 1.5
Foamaster soap L .RTM., defoamer
2 1.0
Total 200 100.0
______________________________________
173 g of the dry mix was used to prepare the wet paste using 33 g Agrimax
3H and 3 g water. Performance and compositions summary is shown in the
Table.
EXAMPLE D
Example A was repeated except the dry charge was as shown in Table 1 below:
______________________________________
Ingredients Wt., g % by Wt.
______________________________________
Chlorothalonil, technical grade
167 83.5
Agrimer XL .RTM. (disintegrant)
8 4.0
Dispersant 1, Reax .RTM. 45 A
10 5.0
Dispersant 2, Lomar .RTM. D
10 5.0
Wetting agent, Morwet .RTM. EFW
3 1.5
Foamaster soap L .RTM. defoamer
2 1.0
Total 200 100.0
______________________________________
168 g of the dry mix was used to prepare the wet paste using 33 g Agrimax
3H and 2.75 g water. Performance and compositions summary is shown in the
Table.
EXAMPLE E
Example A was repeated except the dry charge was as shown in Table 1 below:
______________________________________
Ingredients Wt., g % by Wt.
______________________________________
Chlorothalonil, technical grade
163 81.5
Agrimer XL .RTM., disintegrant
8 4.0
Dispersant 1, Reax .RTM. 45 A
12 6.0
Dispersant 2, Lomar .RTM. D
12 6.0
Wetting agent, Morwet .RTM. EFW
3 1.5
Foamaster soap L .RTM., defoamer
2 1.0
Total 200 100.0
______________________________________
169 g of the dry mix was used to prepare the wet paste using 32 g Agrimax
3H and 3 g water. Performance and compositions summary is shown in the
Table.
EXAMPLE F
Example A was repeated except the dry charge was as shown in Table 1 below:
______________________________________
Ingredients Wt., g % by Wt.
______________________________________
Chlorothalonil, technical grade
159 79.5
Agrimer XL .RTM., disintegrant
8 4.0
Dispersant 1, Reax .RTM. 45 A
16 8.0
Dispersant 2, Lomar .RTM. D
12 6.0
Wetting agent, Morwet .RTM. EFW
3 1.5
Foamaster soap L .RTM. defoamer
2 1.0
Total 200 100.0
______________________________________
174 g of the dry mix was used to prepare the wet paste using 33 g Agrimax
3H and 3 g water. Performance and compositions summary is shown in the
Table.
TABLE 1
__________________________________________________________________________
SUMMARY OF EXAMPLES A-F,
PERCENT WEIGHT COMPOSITIONS OF DRY MIXES
Active
Ingredient,
Dispersant
Dispersant
Wetting
Ex
Technical
1 2 Defoamer
Agent Disintegrant
Buffer
__________________________________________________________________________
A Carbaryl
Reax 45 A
Lomar D
Foamster
Morwet EFW
Agrimer XL
KH.sub.2 PO.sub.4
74.5 8% 6% 1% 1.5% 4% 5%
B Carbaryl
Reax 45 A
Lomar D
Foamster
Morwet EFW
Agrimer XL
KH.sub.2 PO.sub.4
74.5 8% 6% 1% 1.5% 4% 5%
C Chlorotha-
Reax 45 A
Lomar D
Foamster
Morwet EFW
Agrimer XL
lonil 85.5%
5% 3.0% 1% 1.5% 4%
D Chlorotha-
Reax 45 A
Lomar D
Foamster
Morwet EFW
Agrimer XL
lonil 83.5%
5% 3.0% 1% 1.5% 4%
E Chlorotha-
Reax 45 A
Lomar D
Foamster
Morwet EFW
Agrimer XL
lonil 81.5%
6% 6.0% 1% 1.5% 4%
F Chlorotha-
Reax 45 A
Lomar D
Foamster
Morwet EFW
Agrimer XL
lonil 79.5%
8% 6.0% 1% 1.5% 4%
__________________________________________________________________________
NOTES:
Reax .RTM. 45 A (Westvaco) is lignosulfonic acid/sodium salt
Lomar .RTM. D is a polymerized naphthalene sulfonate condensate sodium
salt
Agrimer .RTM. XL is crosslinked polyvinylpyrrolidone
Morwet .RTM. EFW (Witco) is a wetting agent Mixed alkyl naphthalene
sulfonate condensate, sodium salt of carboxylates.
Foamster .RTM. Soap L (Henkel) a tallow soap
Agrimax .RTM. 3H (ISP) a mixture containing long chain alkyl pyrrolidone,
anionic oil soluble dispersing agent, petroleum aromatic distillate and
water insoluble alkylated polyvinylpyrrolidone
3. Test Procedures
Cone Dispersion--15 g. of sample was dispersed in 800 mL of 342 ppm hard
water (hardness equivalent to CaCO.sub.3) by stirring with a magnetic stir
bar for 2 min. The suspension was poured into a 1 L Imhoff dispersion
cone, and allowed to settle for 5 min. The sediment volume was then
determined, and a sedimentation index was calculated as follows
##EQU1##
Crush Strength--Granules were sieved to provide a sample in the -10+12 mesh
range. Granules were placed on balance and crushed firmly with a spatula.
The force registered at breakage was recorded as the crush strength. The
median of 15 to 20 measurements was reported.
Filtration Suspension--A quantity of sample containing 1 g of technical was
added to 250 mL of 342 ppm hard water in a Fleaker.TM.. After 5 min, the
Fleaker.TM. was inverted 30 times to disperse the sample. Immediately, the
suspension was then poured into an Imhoff dispersion cone. After 30 min,
the upper 90% of the suspension was removed by aspiration. The remaining
sample was vacuum filtered through a No. 3 Whatman filter paper, dried,
and weighed to determine residual solids. The percent suspended was
calculated as follows:
##EQU2##
where the sample wt consists only of insoluble components of the
formulation.
Friability--Measurements were carried out on a Vanderkamp.RTM. friabilator.
10 g of sample, initially between 10 and 40 mesh in size, was loaded into
a Roche drum. 25 PFTE balls of 0.6 cm diameter were also loaded into the
drum, which was then attached to the friabilator. The sample was subjected
to 400 rotations, where each rotation causes the sample to fall a distance
of 15 cm. Afterwards, the sample was sieved through a 40 mesh screen, and
the weight of sample remaining above 40 mesh was determined. A friability
index was calculated as follows:
##EQU3##
Foaming--100 mL of 342 ppm hard water and 5 g of sample were added to a 500
mL fleaker. The suspension was shaken vigorously by hand 60 times, and
then allowed to settle for 2 min. The suspension was again shaken 60
times, after which the foam height was measured after 10 s and 2 min. The
last step was repeated to produce a second set of values at 10 s and 2
min. A foaming index was calculated as follows:
##EQU4##
Wet paste compositions and properties of dry granules are summarized in
Table 2 below.
TABLE 2
__________________________________________________________________________
Properties of Dry Granules
Wet Paste Compositions
Cone
Filtr.
Fria-
Dry mix disp
susp bility
Crush
(from Table
Water
Agrimax
(Sed
(% Susp-
(Fri
Strength
Ex.
1%) % % 3H, % Index)
ended)
Index)
(Grams)
__________________________________________________________________________
A 80 0 20 <0.5
73 98 30
B 77.15 0 22.85 <0.5
93.6 95.3
25
C 82.8 1.4 15.8 8.6 59 98 15
D 82.5 1.3 16.2 4 65 97 18
E 82.8 1.5 15.7 1 70 98 18
F 82.9 1.4 15.7 0.7 86 96 12
__________________________________________________________________________
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